1. Field
Aspects of the present invention relate to a cylindrical lithium secondary battery, and more particularly, to a cylindrical lithium secondary battery including a functional center pin.
2. Description of the Related Art
In general, cylindrical lithium secondary batteries include a cylindrical electrode assembly combined with a center pin, a cylindrical can containing the electrode assembly, an electrolyte that is injected into the can to allow lithium ions to move, and a cap assembly connected to one side of the can to prevent the electrolyte from leaking out and the electrode assembly from being displaced. Such cylindrical lithium secondary batteries have a capacity ranging from 2000 to 4000 mA and, thus, are applied to mobile devices with high power consumption (such as notebook computers, digital cameras, and camcorders). For example, a plurality of cylindrical lithium secondary batteries are connected to each other in series or in parallel and assembled with a protective circuit to form a hard pack having a predetermined shape to be used as a power source for mobile devices.
In addition, the cylindrical lithium secondary battery may be manufactured according to the following process. A negative electrode plate coated with a negative electrode active material, a separator, and a positive electrode plate coated with a positive electrode active material are stacked. One end of the stack is bound to a rod-shaped winding axis, and the stack is wound to have a cylindrical shape. Then, a center pin is assembled with the electrode assembly, and the electrode assembly is inserted into the cylindrical can. An electrolyte is subsequently injected into the cylindrical can, and a cap assembly is coupled to the upper portion of the cylindrical can to manufacture the cylindrical lithium secondary battery.
Meanwhile, such cylindrical lithium secondary batteries include a safety vent that is deformed when the internal pressure increases due to an overcharge, and a circuit board that breaks according to the deformation of the safety vent to interrupt current in order to prevent an explosion and an outbreak of a fire caused by the overcharge. In general, the safety vent and the circuit board constitute a current interrupt device (CID), which is an element of the cap assembly.